The electromagnetic coil device may be applied to many fields, for example, may be used as a coil of an electronic expansion valve of a refrigeration system, or as a stator portion of a step motor. In particular, a typical application for the electromagnetic coil device is serving as the coil of the electronic expansion valve of the refrigeration system.
The electronic expansion valve of the refrigeration system generally includes an electromagnetic coil device and a valve body device connected with the electromagnetic coil device. The electromagnetic coil device includes a buckle, and the valve body device includes a fixing frame. The buckle is connected to the fixing frame, so as to achieve the connection between the valve body device and the electromagnetic coil device.
In operation, the electronic expansion valve drives a spool of the valve body device to move through the magnet field generated by energizing the electromagnetic coil device, so as to control the opening action of a valve port.
Referring to FIG. 1, a structural schematic view of a typical electromagnetic coil device in the prior art is shown.
The electromagnetic coil device in the prior art includes a buckle 11. The buckle 11 includes a first horizontal portion 111, a second horizontal portion 112 and a vertical portion 113 connecting the first horizontal portion 111 and the second horizontal portion 112. The electromagnetic coil device further includes a coil body 12 to which the first horizontal portion 111 is fixedly connected by a screw 13.
As can be seen from the above description, the first horizontal portion 111 of the buckle 11 is fixedly connected to the coil body 12 by the screw 13, such a fixed connection with screw is prone to loosen and thus may decrease the reliability of the connection between the coil body 12 and the buckle 11. Therefore, the operating stability of the electromagnetic coil device will be deteriorated and the cost is relatively higher.
In addition, there is another type of electromagnetic coil device in the prior art. In such electromagnetic coil device, the buckle is connected to the coil body by welding instead of the above screw connection. The buckle is made of metal material, such as a stainless steel sheet. A stator case of the coil body is made of magnetic-conductive material, such as a galvanized carbon steel plate. Therefore, the welding between the buckle and the stator case is a dissimilar metal welding, which usually needs to be carried out by a resistance welding.
Since a surface of the stator case has a galvanized coating, requirements for the welding process of the resistance welding are rigorous and the life span of welding electrodes are short. Further, since the buckle is welded to the stator case, the stator case can not be encapsulated with encapsulation material and thus have to be exposed to the atmosphere. When the stator case and the buckle are welded together, the stator case usually is subject to electrochemical corrosion, because they are made of different materials and have different electrode potential differences.